[wp-testers] wp_list_authors()?

[Foolish Visions]

I'm trying to use wp_list_authors on a theme I'm developing, and it's not returning anything - not even an error.  Just to check, I tried using the default theme, as well as TwentyTen, (and yes, deactivated all plugins I'm using - oh, and I'm using RC2) and it's the same in both of those themes as well - wp_list_authors() is ignored. 

Did I miss something? Or..well I dunno what, actually :) 

In the end, really all I need is to obtain a list of all blog user ID's.  I have a custom field set for each user (I want to have posts appear in a particular order, so I'm using a custom user_meta to set the order) and I just need to grab the user ID's so I can query and arrange by the custom value.  I was thinking I could use a non-echoed wp_list_authors to get the array of users - but it's returning absolutely nothing at all.  I have debugging on, and although I'm getting a lot of notices and warnings about other stuff, this function is still treated like it's not even there.

Any ideas, pretty please? (or is it as simple as "drink more coffee and pay attention"?)

~Shelly